650R fuel or air ?

can someone tell me if the screw on the right side of the carb (stock), the pilot screw, is afecting the fuel or the air? after I have done some search I have seen different answers. Can someone that is only 100% certain answer me...

I taugh it was a fuel screw, meaning open it would enriched the mix, so it would or run cooler but it did the oposite my vapor read higher temp with that srew turn out more... so I'm now thinking that it actually gave it more air???

just open my air box and want to give it a little more fuel.


personally i would not use the pilot screw as an engine temperature adjustment. it is there to make the engine run CORRECT, not COOL. clockwise makes it leaner, counterclockwise makes it richer.

Before the throttle valve are air screws, after the throttle valve are fuel screws typically.

I'm fairly certain it's a fuel screw.

That screw(which controls fuel) is only going to alter mixture at idle and off-idle where the airflow mods have little affect. You need to address the jets.

Agree with HT on that.........you just opened the airbox,you let more air flow in.......now it`s running leaner which means hotter......the fuel screw will make it idle better.......but you need to rejet to correct the lean condition...


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now